Synchronous measurements of renal function and T-cell subsets were taken in 51 cases of chronic renal failure (CRF) patients. Cordyceps sinesis 3-5 g/d was given to 28 out of these 51 patients, which was considered as follow-up group. The results were stated as follows: (1) Obvious decrease of OKT3, OKT4, OKT4/OKT8 was found in CRF (P < 0.01). (2) OKT4 and OKT4/OKT8 were proportional to plasma albumin and Hb levels (P < 0.05). (3) After administration of Cordyceps sinesis, improvement of renal function and OKT4, OKT4/OKT8 were confirmed. This study indicated that cellular immune function was decreased in CRF. Administration of Cordyceps sinesis might improve their renal function and as the same time enhance the cellular immune function in CRF.